using PHP Version 5.3.5
I am going insane.
This piece of code is giving me hard time. After I refresh the page on Apache a few times, I get weird results. I think I have a memory leak here, but I can't find out why.
Please help !
<?php
function ost($active_sub_time,$arr_subscription_values)
{
$result=0;
while($active_sub_time>=12)
{
$active_sub_time-=12;
$result+=($arr_subscription_values['COST_12']);
}
while($active_sub_time>=6)
{
$active_sub_time-=6;
$result+=($arr_subscription_values['COST_6']);
}
while($active_sub_time>=3)
{
$active_sub_time-=3;
$result+=($arr_subscription_values['COST_3']);
}
while($active_sub_time>=1)
{
$active_sub_time-=1;
$result+=($arr_subscription_values['COST_1']);
}
if($active_sub_time>0)
$result+=($active_sub_time)*($arr_subscription_values['COST_1']);
if (!is_numeric($result))
{
echo"<br> Bug occurred";break; // print other values if necessary
}
return $result;
}
$datetime1 = date_create('2009-01-11');
$datetime2 = date_create('2001-11-09');
$interval = date_diff($datetime1, $datetime2);
$num_of_months = ($interval->y)*12 + ($interval->m) + ($interval->d)/(cal_days_in_month(CAL_GREGORIAN, $datetime2->format("m"), $datetime2->format("Y")));
$v = array('COST_1'=>'3.99','COST_3'=>'9.99','COST_6'=>'15.99','COST_12'=>'24.99');
echo "OPT value for $num_of_months months=".ost($num_of_months,$v);
?>
I do get this result at first:
OPT value for 86.066666666667 months=183.176
But after a few refreshes I get this :
OPT value for G.GMMMMMMMMMMMN months=183.176
Does anyone know why this is ?
Thanks
Cannot reproduce, I used your code exactly, and executed it multiple times. It displays the same result.
There may be an issue with your server, or mashing refresh over and over is causing some kind of problem or memory limit.
Check your php.ini and see if your memory limit is set too low, or max requests?
Related
I was looking at execution time of some functions, but i have found that microtime is getting wrong, in one microtime()
implementation №1 always first time is always getting more then second microtime() executing, when i testing one function and saw that one case is faster then another, but after place replace (2nd function to 1st place), it getting slower anyway, even if it was 3x faster...
function dotimes($times,$eval,$data=false) {for(;--$times;) eval($eval);}
$start = microtime(true);
dotimes(1000,'$i = $i?$times/2:1;');
printf(": executed : %f\n",microtime(true)-$start);
$start = microtime(true);
dotimes(1000,'$i = $i?$times/2:1;');
printf(": executed : %f\n",microtime(true)-$start);
// 1st case is always slower...
implementation №2 iv made sometimes before microtime() as static data storage, but in that case the time of execute is always second time is slower then first (oposite to implementation №1)
function get_execution_time()
{
static $microtime_start = null;
return $microtime_start === null ? $microtime_start = microtime(true) : microtime(true) - $microtime_start;
}
function dotimes($times,$eval,$data=false) {for(;--$times;) eval($eval);}
get_execution_time();
dotimes(1000,'$i = $i?$times/2:1;');
printf(": executed : %f\n<br>",get_execution_time());
get_execution_time();
dotimes(1000,'$i = $i?$times/2:1;');
printf(": executed : %f\n<br>",get_execution_time());
//now 2nd case is faster..
Can somebody tell me what is going up? Why these microtimes in one case 1st always slower, and throught static storage 2nd execute is slow down, WHY?
ps if someone need tiny mt function here is my FIXED AND WORKING CORRECT:
function get_mt() {static $mt; return $mt ? microtime(true)-$mt.$mt=null : $mt=microtime(true);}
attached :
function get_mt() {static $mt; return $mt?microtime(true)-$mt:$mt=microtime(true);}
function dotimes($times,$eval,$data=false) {for(;--$times;) eval($eval);}
$start = microtime(true);
get_mt();
dotimes(10000,'$i = $i?$times/2:1;');
printf(":clean executed : %f\n<br>",microtime(true)-$start);
printf(":static executed : %f\n<br>",get_mt());
$start = microtime(true);
get_mt();
dotimes(10000,'$i = $i?$times/2:1;');
printf(":clean executed : %f\n<br>",microtime(true)-$start);
printf(":static executed : %f\n<br>",get_mt());
So far, I see that implementation №1 is correct. No clue what you tried in your second implementation.
The advice here - never test two cases in the same script. Run them separately a few times and then find the average time. PHP allocates memory when it needs and this is a slow operation. The second case may reuse already allocated memory and skip this operation and you get wrong results.
static makes a variable semi global within that function retative to function name.
I would say the delay goes in the fact that the static array needs to be checked for the previous value of the static variable.
extra work == delay
I wrote this PHP function:
<?php
//windows cpu temperature
function win_cpu_temp(){
$wmi = new COM("winmgmts://./root\WMI");
$cpus = $wmi->execquery("SELECT * FROM MSAcpi_ThermalZoneTemperature");
foreach ($cpus as $cpu) {
$cpupre = $cpu->CurrentTemperature;
}
$cpu_temp = ($cpupre/10)-273.15 . ' C';
return $cpu_temp;
}
echo win_cpu_temp();
?>
My problem, is that the script displays 59.55 C which I had thought was correct. I checked this value several hours later, and it's exactly the same. I just put the CPU to work at 90% compressing video for ten minutes, and this value is the same still.
Can anyone help me find the "true" value for this function?
I've read (to no avail):
MSAcpi_ThermalZoneTemperature class not showing actual temperature
How is, say, "Core Temp" getting its values? Same computer, it reports between 49 and 53 Celsius.
With a little digging around I found the common issue with using MSAcpi_ThermalZoneTemperature was that it is dependent upon being implemented on your system.
You could try querying Win32_TemperatureProbe and see if you have any luck there.
Neither MSAcpi_ThermalZoneTemperature or Win32_TemperatureProbe worked on my system, although if you have admin access, you can use http://openhardwaremonitor.org/ which provides a WMI interface for all available sensor data.
This worked great for me and I was able to accurately report CPU Core temp from a PHP script:
function report_cpu_temp(){
$wmi = new COM('winmgmts://./root/OpenHardwareMonitor');
$result = $wmi->ExecQuery("SELECT * FROM Sensor");
foreach($result as $obj){
if($obj->SensorType == 'Temperature' && strpos($obj->Parent, 'cpu') > 0)
echo "$obj->Name ($obj->Value C)"; // output cpu core temp
else
echo 'skipping ' . $obj->Identifier ;
echo '<br />';
}
}
Hope this helps.
I have this loop to long poll:
$time = time(); //send a blank response after 15sec
while((time() - $time) < 15) {
$last_modif = filemtime("./logs.txt");
if($_SESSION['lasttime'] != $last_modif) {
$_SESSION['lasttime'] = $last_modif;
$logs = file_get_contents("./logs.txt");
print nl2br($logs);
ob_flush();
flush();
die();
}
usleep(10000);
}
problem is: the "if" condition is never entered in the middle of the while loop, even if logs.txt is modified. I have to wait 15sec till the next call to this file to obtain the updated content (so it becomes a regular, "setTimeout style" AJAX polling, not a long-poll). Any idea why ?
This is because of the filemtime() function : its results are cached. Thus each time your loop is executed the timestamp's the same for 15 seconds.
I have not tried it myself, but according to w3cschools :
The result of this function are cached. Use clearstatcache() to clear the cache.
Hope that helps !
I am running subscriptions on my website.
I have a 1,3,6 and 12 months of subscription, and I would like the user to be able to change that subscription whenever they feel like.
However, I need to calculate the amount of money the user had to pay had he or she signed up for the shorter term, rather the relatively cheap,longer one.
I made this function optimized_subscription_total($active_sub_time,$arr_sub_values) so that it returns that sum of money exactly.
<?php
function optimized_subscription_total($active_sub_time,$arr_sub_values)
{
// This function takes a row from the DB where prices for each period of time usage is listed. there are prices for 1 month, 3 months,6 and 12 months.
// when the user has subscribed for 12 months, and the user asks for a refund, after they used 9 months and 6 days for example, the system treats the refund as if they subscribed for (in months) COST_6 + COST_3 + (COST_1/30)*6
// the result of the function is then subtracted from the amount they actually paid and is considered the refund.
// $arr_sub_values is the associative row from the DB, containing the prices
// $active_sub_time is measured in months and is a double
$result=0;
while(($active_sub_time-12)>=0)
{
$active_sub_time-=12;
$result+=($arr_subscription_values['COST_12']);
}
while(($active_sub_time-6)>=0)
{
$active_sub_time-=6;
$result+=($arr_subscription_values['COST_6']);
}
while(($active_sub_time-3)>=0)
{
$active_sub_time-=3;
$result+=($arr_subscription_values['COST_3']);
}
while(($active_sub_time-1)>=0)
{
$active_sub_time-=1;
$result+=($arr_subscription_values['COST_1']);
}
if($active_sub_time>0)
$result+=($active_sub_time)*($arr_subscription_values['COST_1']);
return $result;
}
$datetime1 = date_create('2009-12-11');
$datetime2 = date_create('2010-11-09');
$interval = date_diff($datetime1, $datetime2);
$num_of_months = ($interval->format('%y'))*12+($interval->format('%m'))+($interval->format('%a'))/30;
echo "<br />";
$v = array('COST_1'=>'3.99','COST_3'=>'9.99','COST_6'=>'15.99','COST_12'=>'25.99');
echo "OPT value for $num_of_months months=" . optimized_subscription_total($num_of_months, $v);
?>
Strangely I get the bug appearing only after 7 to 10 times after refreshing this code.
So I got:
OPT value for 10 months=M.97
as a result here. I think I need to get a float number, no ?
I was expecting the result of the function that should be "OPT value for 10 months=29.97", as it should take COST_6 + COST_3 + COST_1... but I get that weird M.97, and sometimes things like POKHHHG.97
I would change the logic to the following and see if error is still produced. I think this is a little bit more clear and easy to debug. It is the same as your though just explained differently.
while($active_sub_time>=12)
{
$active_sub_time-=12;
$result+=($arr_subscription_values['COST_12']);
}
while($active_sub_time>=6)
{
$active_sub_time-=6;
$result+=($arr_subscription_values['COST_6']);
}
while($active_sub_time>=3)
{
$active_sub_time-=3;
$result+=($arr_subscription_values['COST_3']);
}
while($active_sub_time>=1)
{
$active_sub_time-=1;
$result+=($arr_subscription_values['COST_1']);
}
What I would also do is added debug cod at the top inside function.
echo "<br>$active_sub_time" // debug code include at the top
This will give you an idea, if any garbage being is being sent to the function itself.
Also I would add this test function in all while blocks if the above does not resolve the issue.
if (!is_numeric($result))
{
echo"<br> Bug occurred";break; // print other values if necessary
}
I've had some issues lately with PHP memory limits lately:
Out of memory (allocated 22544384) (tried to allocate 232 bytes)
These are quite the nuisance to debug since I'm not left with a lot of info about what caused the issue.
Adding a shutdown function has helped
register_shutdown_function('shutdown');
then, using error_get_last(); I can obtain information about the last error, in this case, the "Out of memory" fatal error, such as the line number, and the php file name.
This is nice and all, but my php program is heavily object oriented. An error deep in the stack doesn't tell me much about the control structure or the execution stack at the moment of the error. I've tried debug_backtrace(), but that just shows me the stack during shutdown, not the stack at the time of the error.
I know I can just raise the memory limit using ini_set or modifying php.ini, but that doesn't get me any closer to actually figuring out what is consuming so much memory or what my execution flow looks like during the error.
Anyone have a good methodology for debugging memory errors in advanced Object Oriented PHP programs?
echo '<pre>';
$vars = get_defined_vars();
foreach($vars as $name=>$var)
{
echo '<strong>' . $name . '</strong>: ' . strlen(serialize($var)) . '<br />';
}
exit();
/* ... Code that triggers memory error ... */
I use this to print out a list of currently assigned variables just before a problem section of my code, along with a (very) rough estimate of the size of the variable. I go back and unset anything that isn't needed at and beyond the point of interest.
It's useful when installing an extension isn't an option.
You could modify the above code to use memory_get_usage in a way that will give you a different estimate of the memory in a variable, not sure whether it'd be better or worse.
Memprof is a php extension that helps finding those memory-eaters snippets, specially in object-oriented codes.
This adapted tutorial is quite useful.
Note: I unsuccessfully tried to compile this extension for windows. If you try so, be sure your php is not thread safe. To avoid some headaches I suggest you to use it under *nix environments.
Another interesting link was a slideshare describing how php handles memory. It gives you some clues about your script's memory usage.
I wonder is perhaps your thinking regards methodology is flawed here.
The basic answer to your question - how do I find out where this error is occurring? - has already been answered; you know what's causing that.
However, this is one of those cases where the triggering error isn't really the problem - certainly, that 232 byte object isn't your problem at all. It is the 20+Megs that was allocated before it.
There have been some ideas posted which can help you track that down; you really need to look "higher level" here, at the application architecture, and not just at individual functions.
It may be that your application requires more memory to do what it does, with the user load you have. Or it may be that there are some real memory hogs that are unnecessary - but you have to know what is necessary or not to answer that question.
That basically means going line-by-line, object-by-object, profiling as needed, until you find what you seek; big memory users. Note that there might not be one or two big items... if only it were so easy! Once you find the memory-hogs, you then have to figure out if they can be optimized. If not, then you need more memory.
Check the documentation of the function memory_get_usage() to view the memory usage in run time.
Website "IF !1 0" provides a simple to use MemoryUsageInformation class. It is very useful for debugging memory leaks.
<?php
class MemoryUsageInformation
{
private $real_usage;
private $statistics = array();
// Memory Usage Information constructor
public function __construct($real_usage = false)
{
$this->real_usage = $real_usage;
}
// Returns current memory usage with or without styling
public function getCurrentMemoryUsage($with_style = true)
{
$mem = memory_get_usage($this->real_usage);
return ($with_style) ? $this->byteFormat($mem) : $mem;
}
// Returns peak of memory usage
public function getPeakMemoryUsage($with_style = true)
{
$mem = memory_get_peak_usage($this->real_usage);
return ($with_style) ? $this->byteFormat($mem) : $mem;
}
// Set memory usage with info
public function setMemoryUsage($info = '')
{
$this->statistics[] = array('time' => time(),
'info' => $info,
'memory_usage' => $this->getCurrentMemoryUsage());
}
// Print all memory usage info and memory limit and
public function printMemoryUsageInformation()
{
foreach ($this->statistics as $satistic)
{
echo "Time: " . $satistic['time'] .
" | Memory Usage: " . $satistic['memory_usage'] .
" | Info: " . $satistic['info'];
echo "\n";
}
echo "\n\n";
echo "Peak of memory usage: " . $this->getPeakMemoryUsage();
echo "\n\n";
}
// Set start with default info or some custom info
public function setStart($info = 'Initial Memory Usage')
{
$this->setMemoryUsage($info);
}
// Set end with default info or some custom info
public function setEnd($info = 'Memory Usage at the End')
{
$this->setMemoryUsage($info);
}
// Byte formatting
private function byteFormat($bytes, $unit = "", $decimals = 2)
{
$units = array('B' => 0, 'KB' => 1, 'MB' => 2, 'GB' => 3, 'TB' => 4,
'PB' => 5, 'EB' => 6, 'ZB' => 7, 'YB' => 8);
$value = 0;
if ($bytes > 0)
{
// Generate automatic prefix by bytes
// If wrong prefix given
if (!array_key_exists($unit, $units))
{
$pow = floor(log($bytes) / log(1024));
$unit = array_search($pow, $units);
}
// Calculate byte value by prefix
$value = ($bytes / pow(1024, floor($units[$unit])));
}
// If decimals is not numeric or decimals is less than 0
// then set default value
if (!is_numeric($decimals) || $decimals < 0)
{
$decimals = 2;
}
// Format output
return sprintf('%.' . $decimals . 'f ' . $unit, $value);
}
}
Use xdebug to profile memory usage.